In Clements v Clements, Justice of Canada's Supreme Court used these words to offer a neat summary of the law and the context in which the concept of but for appies in tort law:

"Recovery in negligence presupposes a relationship between the plaintiff and defendant based on the existence of a duty of care — a defendant who is at fault and a plaintiff who has been injured by that fault. If the defendant breaches this duty and thereby causes injury to the plaintiff, the law corrects the deficiency in the relationship by requiring the defendant to compensate the plaintiff for the injury suffered. This basis for recovery, sometimes referred to as corrective justice, assigns liability when the plaintiff and defendant are linked in a correlative relationship of doer and sufferer of the same harm.

"The test for showing causation is the but fortest. The plaintiff must show on a balance of probabilities that but for the defendant’s negligent act, the injury would not have occurred.

"Inherent in the phrase but for is the requirement that the defendant’s negligence was necessary to bring about the injury ? in other words that the injury would not have occurred without the defendant’s negligence. This is a factual inquiry. If the plaintiff does not establish this on a balance of probabilities, having regard to all the evidence, her action against the defendant fails.

"The but for causation test must be applied in a robust common sense fashion. There is no need for scientific evidence of the precise contribution the defendant’s negligence made to the injury.

"A common sense inference of but for causation from proof of negligence usually flows without difficulty. Evidence connecting the breach of duty to the injury suffered may permit the judge, depending on the circumstances, to infer that the defendant’s negligence probably caused the loss.

"Where but for causation is established by inference only, it is open to the defendant to argue or call evidence that the accident would have happened without the defendant’s negligence, i.e. that the negligence was not a necessary cause of the injury, which was, in any event, inevitable."

"The but for test has been accepted as an appropriate method of deciding causation in negligence cases....

"It asks the question -- would the accident have occurred but for the defendant's negligence? If the answer is that the accident would have occurred even without the defendant's negligence, there is no causation."

When suing for negligence, a plaintiff must show that the actions of the alleged tort feasor (who will be the defendant in the tort action) caused the injury or damages the plaintiff suffered.

May also be referred to as the sine quo non (without which not) test and in American law, the but for test is at times also referred to as "factual causation".

"... the plaintiff must prove on a balance of probabilities that, but for the tortious conduct of the defendant, the plaintiff would not have sustained the injury complained of."

Where the "but for" test cannot be applied, such as where there are more than one contributing factor, it may be possible to presume causation anyway under the doctrine of a 2007 Supreme Court of Canada case, Resurfice v Hanke, 2007 SCC 7 and which also restarted the but for test adopting these words:

"The basic test for determining causation remains the but for test. This applies to multi-cause injuries. The plaintiff bears the burden of showing that "but for" the negligent act or omission of each defendant, the injury would not have occurred. Having done this, contributory negligence may be apportioned, as permitted by statute.

"This fundamental rule has never been displaced and remains the primary test for causation in negligence actions.

"(T)he general, but not conclusive, test for causation is the but for test, which requires the plaintiff to show that the injury would not have occurred but for the negligence of the defendant". Similarly ... the rules of causation consider generally whether ‘but for’ the defendant’s acts, the plaintiff’s damages would have been incurred on a balance of probabilities.

"The but for test recognizes that compensation for negligent conduct should only be made where a substantial connection between the injury and the defendant’s conduct is present. It ensures that a defendant will not be held liable for the plaintiff’s injuries where they may very well be due to factors unconnected to the defendant and not the fault of anyone...."

Categories & Topics:

If you find an error or omission in Duhaime's Law Dictionary, or if you have suggestion for a legal term, we'd love to hear from you!

LAWimage

Sort By:

The template you are linking to has no template configured yet.

Duhaime Lawisms

The case is this. A large portion of the body of the law was, by the bigotry or artifice of lawyers, locked up in an illegible character, and in a
foreign tongue. The statute (Blackstone) mentions obliged them to give up their hieroglyphics, and to restore the native language to its rights. This was doing much; but it was not doing everything. Fiction, tautology, technicality, circuity, irregularity, inconsistency remain. But above all, the
pestilential breath of Fiction poisons the sense of every instrument it comes near.
Jeremy Bentham, A Comment on the Commentaries (Blackstone)

Expand Navigation

Unless otherwise noted, this article was written by Lloyd Duhaime, Barrister, Solicitor, Attorney and Lawyer (and Notary Public!). It is not intended to be legal advice and you would be foolhardy to rely on it in respect to any specific situation you or an acquaintance may be facing. In addition, the law changes rapidly and sometimes with little notice so from time to time, an article may not be up to date. Therefore, this is merely legal information designed to educate the reader. If you have a real situation, this information will serve as a good springboard to get legal advice from a lawyer.